The book is one of the more comprehensive of its kind and features 1000 of the historically most important chairs (and a handful of sofas, chaise longues, etc.). It begins in 1808 and goes on right into the current millenium and will pretty much feature every important designer piece.
In typical Taschen style it is trilingual (English, German, French), has a short introduction on the evolution of the chair, the styles, etc. and then delves into the body - i.e. the 1000 chairs - which get a picture each, a description of the materials used, year first produced, manufacturer / designer and a short text on where the chairs fit in or what the designer was trying to achieve. Many chairs get a full page to themselves, with some pages featuring two chairs by the same designer (how you fit 1000 chairs onto ca. 600 pages).
The book is very useful for getting interior decoration ideas, will be a must have / must know for a design student and is a good source for identifying chairs you have seen elsewhere. Speaking of which, the chairs are arranged by year of first manufacture, and while there is an alphabetical index at the back, that will only help if you kow the chair's or designer's name, otherwise be prepared for frequent thumbing through to find what you are looking for - a spotters book this is not.